This application is the U.S. National Phase of International Application Number PCT/NL00/00377 filed on Jun. 5, 2000, which is incorporated herein by reference.
This invention relates to a system for determining process parameters relating to thermal combustion processes of matter such as, for instance, waste in an incinerator, comprising sensor means and a computer coupled thereto for determining the parameters, wherein, in use, matter having a combustible part CHYOz is supplied to the incinerator and combusted, thereby forming a flue gas.
This invention relates to a system for determining process parameters relating to thermal combustion processes of matter such as, for instance, waste in an incinerator, comprising sensor means and a computer coupled thereto for determining the parameters, wherein, in use, matter having a combustible part CHyOz is supplied to the incinerator and combusted, thereby forming a flue gas.
Operational management of the existing plants for waste incineration is rendered more difficult by the varying composition of the waste that is supplied to an incinerator of the plant. Due to the circumstance that changes in the properties of the waste are not recognized timely in the process behavior, the existing control systems are not properly able to regulate the process.
If, however, the waste composition of the waste in the incinerator could be derived on-line, this would enable better adjustment to variations in the waste composition, thereby rendering the waste incineration process better controllable. Such a derivation, however, is highly complicated.
The object of the invention is to provide a system that can be utilized in a plant for combustion of matter to meet the drawbacks outlined. Accordingly, the system for determining process parameters relating to the thermal combustion of matter is characterized in that the sensor means are arranged for measuring the fractions XCO2, XO2 and XH2O in the flue gas and that the computer is arranged for determining, on the basis of the measured fractions, the composition (y/z) and/or the heat of combustion (HCHyOz, [J/kg]) of the combustible part CHyOz, with XO2, XH2O, XCO2 respectively representing the fractions of O2, H2O and CO2 in the flue gas.
The object of the invention is to provide a system that can be utilized in a plant for combustion of matter to meet the drawbacks outlined. Accordingly, the system for determining process parameters relating to the thermal combustion of matter is characterized in that the sensor means are arranged for measuring the fractions XCO2, XO2 and XH2O in the flue gas and that the computer is arranged for determining, on the basis of the measured fractions, the composition (y/z) and/or the heat of combustion (HCHyOz, [J/kg]) of the combustible part CHyOz, with XO2, XH2O, XCO2 respectively representing the fractions of O2, H2O and CO2 in the flue gas.
By measuring, in accordance with the invention, just the fractions XCO2, XO2 and XH2O in the flue gas, relevant parameters (the heat of combustion and/or the composition of the combustible part) for possible regulation of the matter combustion can be determined. More particularly, it holds that, in use, the computer calculates the value of Z on the basis of the formulae:       z    =                  2        ·        Xc            +                        1          2                ·        y            -                        2          ·                      X            C                    ·                      X                          N              ⁢              2                                ·                      X                          02              ,              air                                                            X                          CO              ⁢              2                                ·                      X                          N2              ,              air                                          +                        2          ·                      X            C                    ·                      X                          O              ⁢              2                                                X                      CO            ⁢            2                                ;
and
XN2=1xe2x88x92XO2xe2x88x92XH2Oxe2x88x92XCO2
wherein XO2,air (the oxygen fraction in air supplied to the incinerator), XN2,air (the nitrogen fraction in air supplied to the incinerator), Xc (the uncombusted fraction of carbon) and y are predetermined values. Preferably, it will then hold that the predetermined value of Xc is inbetween 0.9 and 1. Further, it holds in particular that, in use, the computer calculates the value of HCHyOz on the basis of the formulae             H      CHyOz        =                            408.4          +                      102.4            ·            y                    -                      156.8            ·            z                                    M          CHyOz                    ·              10        3              ;
and
MCHyOz=0.012+0.001y+0.016z.
According to a further advanced embodiment of the system, it holds that the system further comprises sensor means for determining the air flow "PHgr"tot of the air which, in use, is supplied to the incinerator, the computer being arranged to determine on the basis of the measured fractions XCO2, XO2 and XH2O, the ash-free heating value (Hwaste,ash-free, [J/kg ash-free]) and/or, further on the basis of the measured air flow "PHgr"tot, the amount of heat (Qheat, [W]) which is released upon the combustion. More particularly, it holds further that the computer is further arranged for further determining, on the basis of the predetermined value of the inert fraction of the waste (Xinert, [kg inert/kg waste]), the following four parameters: the waste flow ("PHgr"waste, [kg/s]), the moisture fraction of the waste (XH2O,waste, [kg water/kg waste]), the heating value of the total waste (Hwaste, [J/kg waste]) and/or the fraction of uncombusted (Xuncombusted, [kg uncombusted/kg ash]).
On the basis of one or more of the above-mentioned parameters as determined by the computer, the waste incineration plant can be controlled in a manner known per se, such that combustion is optimal.